[This post is part of a series about our net-zero residential solar project – see a list of links to the full series here, a list of frequently asked questions here or click here to bring up all Green-related posts. Previous Post in Series / Next Post in Series.]
For a conceptually simple system with no moving parts, a solar array system is actually surprisingly complicated to install. Perhaps things will change over time, but at the moment it takes a lot of manual labor to mesh gee whiz technology with the physical realities of a residential roof and electrical system.
Before anything can get started, any necessary tree work has to be done and the parts have to be shipped. And “parts” means pallets – this is a ton of stuff. As in, an entire garage bay’s worth. Below is a shot of our materials upon arrival. That giant mass the panel is leaning against is a flat stack of panels in shrink-wrap. To the left is a second wooden pallet with inverters and other electronics, behind that is a third pallet with a shorter stack of panels, and at the bottom of the photo and sticking out in the lower right are the tons of boxes of rails. A great deal of miscellaneous hardware, clamps, brackets and spools of wiring were brought to the job separately.
When your crew first shows up, they spend literally days working on two key things at once: installing rails and rough electrical work. Installed panels sit on a superstructure of straight rails attached to the roof, and the array of panels send the electricity down via a conduit which must be installed on the outside of the house (or the inside if you want to drill a hole in your roof and route it down internally). The rails are very labor intensive – they provide the both the alignment and the strength of the system. Here’s a photo mosaic of some of the rail installation:
The rough electrical involves a ton of work beyond the conduit; there is an outdoor kill switch, extra meters (a mechanical revenue-grade production monitor, and an electronic production meter tied to the internet), the massive inverters, and all the circuit tie-ins and connections. On top of all that, I took the opportunity to add a very cool Powerhouse Dynamics eMonitor system to give me circuit-by-circuit level detail on live power consumption throughout the house (disclosure: Powerhouse Dynamics is an investment portfolio company of mine – more on them later in a future post on conservation/consumption). The electrical panel work was particularly tricky in our case because we had a relatively small panel area with a fair amount of equipment on it to start with. We had to extend the panel mounting area and then move components around to make space. The result is a fairly tight arrangement:
Needless to say, all this work is time-consuming. Although we had a crew of three or four people from Independent Power Systems working really hard and very steadily, it still felt like forever before we were ready to put any silicon on the roof. For someone who has wanted a solar roof his entire life, it was painful to be so close and have to wait just that little bit longer. We also had some rain which caused a little delay – rain makes a metal roof far too slippery and dangerous to work on without harnesses, and harnesses aren’t practical until there is a first row of rail to connect the harness to. But eventually we got through all the rough work and were ready to begin installing panels:
The actual panel installation itself only took two days. Below is a one-minute time-lapse video of just the two days when we were primarily installing panels, yet, still you can still see how much work goes into rail prep and adjustment even at that point:
Once all the panels are installed and hooked up and the finish electrical work is done, the final stage is testing and electrical inspection. Powering up the system requires making sure the outside switch is on, throwing several AC breakers on the electrical panels, then switching on the two main DC circuits to allow the DC to flow down into the system from the roof. The inverters are designed to put out power at a slightly higher voltage than the outside power coming in from the utility so that your house uses that solar power first and then sends any surplus out onto the grid.
Our system powered up fine, so all we had to do was wait for the town to send an inspector to certify the electrical work, and then once that was done, have the utility come install a net meter. Prior to installation of a net meter, your electrical meter has no awareness of the direction of current – it just measures whatever is flowing, regardless of direction. If you switch your system on at that point, you actually pay MORE for power since the outbound surplus power you produce spins your meter faster and you get billed for that even though it is going outbound!
Once your net meter is installed, you turn the system on and look forward to the sun coming up the next morning…
[This post is part of a series about our net-zero residential solar project – see a list of links to the full series here, a list of frequently asked questions here or click here to bring up all Green-related posts. Previous Post in Series / Next Post in Series.]
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